Considerable resources have been invested over the years to improve irrigation controllers, especially with respect to increasing sophistication of the watering schedules. Modem controllers, for example, may manipulate half a dozen or more valves, may have multiple on/off periods during the day, may have different watering schedules from day to day during the week.
One undesirable side effect of the trend towards increasingly sophisticated controllers is that the inputs needed to drive such controllers are also becoming more complex. Typical modern controllers require a user to separately specify start times and durations for irrigation intervals for each zone, and possibly for each day of the week. Modem controllers may also take into account inputs from external sensors, such as temperature, wind, precipitation and soil moisture sensors. Still further, systems are also known which receive input from a local or distal signal source, such as a radio transmitter. Exemplary disclosures are U.S. Pat. No. 4,962,522, issued October 1990, and U.S. Pat. No. 5,208,855, issued May 1993, both to Marian, and each of which is incorporated by reference herein in its totality. Such systems offer considerable advantages, including the ability to integrate historical rainfall and other data with current estimated evaporative transpiration (evapotranspiration) rates. Systems which receive distal signal inputs can also provide location specific information, such as by ZIP code.
The large quantity of external data makes irrigation controllers relatively complicated to use, and even systems touting automatic adjustment of irrigation flow still require relatively complicated input. Systems discussed in the U.S. Pat. No. 5,208,855, for example, merely update an interval used for preset irrigation control timings, rather than determine an entirely new irrigation schedule. Similarly, systems discussed in U.S. Pat. No. 5,444,611 to Woytowitz et al. (August, 1995) are said to automatically calculate and execute a new schedule, but the new schedule is still based upon programming of a start time. Systems disclosed in U.S. Pat. No. 4,646,224 automatically determine the number of cycles and length of time of each cycle that water is to be applied, but still requires the operator to provide data concerning desired sprinkling days, soil type, the type of sprinkler for each zone, and so forth.
The trend towards increasingly sophisticated controllers is accompanied by a trend towards having ever fewer input controls accessible to the user. Decreasing the number of input controls may reduce the cost and size of a controller unit, but it also adds to the complexity of using the unit. The whole process of adjusting a modern irrigation controller can be compared to programming a VCR. It may be advantageous to have available a large number of different functions, but controlling all of those functions using only half a dozen or so buttons is extremely difficult for many individuals. This problem has been resolved to some extent in VCR controllers by utilizing the TV screen as an interactive display, but that approach is not readily adaptable to common household or other irrigation controllers where a relatively small, inexpensive display screen is employed to reduce costs.
Even if the process of modifying controller parameters were not complex, determining appropriate values for the required input parameters may be exceedingly complex. As an example, modifying a watering duration value to provide more water to a particular irrigation zone might involve all of the following steps: (1) determining the total of all the watering durations currently programmed for the zone over the course of a week; (2) estimating an appropriate change in the amount of water to be applied to the zone; (3) translating that amount into a percentage increase over the presently programmed total; (4) translating such percentages into changes in durations and deciding how such changes in durations should be distributed over the existing schedule; and (5) entering the scheduling changes. Step 4 is particularly difficult for many individuals because there are often no established guidelines for deciding among various options. Thus, a user may have insufficient knowledge to decide between reducing the watering for each day by 10 minutes, or eliminating watering entirely two days per week.
In short, the steadily increasing sophistication of irrigation controller outputs, coupled with the steadily increasing difficulty of operating such controllers, is a significant problem for users. Thus, there is a continuing need to provide sophisticated irrigation control, while providing simple operator input.